Piston pump



United States Patent 3,510,235 PISTON PUMP Wolf-Dieter Bensinger, Stuttgart-Riedenberg, and Helmut Dobler, Stuttgart-Mohringen, Germany, assignors to Daimler-Benz Aktiengesellschaft, Stuttgart-Unterturkheim, Germany Filed Sept. 25, 1968, Ser. No. 762,429 Int. Cl. F0413 7/06 19/22, 49/00 US. Cl. 417-462 16 Claims ABSTRACT OF THE DISCLOSURE A piston pump which includes a fixed pump piston and a reciprocating pump cylinder that simultaneously rotates and thereby controls the inlet and outlet of the pump; the stroke movements of the pump cylinder are derived from the rotary movement of the cylinder with the aid of a force-locking guidance of a control pin eccentrically secured at the cylinder on a control surface and the control surface having approximately the shape of a cylinder surface.

face and the pump cylinder thereby moves to and fro only once during a complete rotation, it is proposed according to the present invention that the control surface has the shape of a cylinder surface. In this manner, two complete stroke movements of the pump cylinder are achieved with the most simple means during a complete rotation of the pump cylinder which permits the metered supply of two lubricating oil lines for each pump working space. Since with the known pumps, one working space each is present above and below the fixed piston and since the prior art pump thus supplies two lubricating oil lines, four lubricating oil lines can be supplied by the changes in accordance with the present invention without additional weight or additional space requirement.

A simple manufacture and assembly results if the cylinder surface is provided at a bolt inserted into the pump housing transversely to the pump cylinder axis whereby one is not restricted in the selection of the cylinder superficies to the bolt radius but one can without difiiculty keep the radius of the cylinder surface larger than the radius of the bolt by a corresponding flattening of the bolt cross section. I

The adjustment of the pump cylinder stroke and therewith the supply quantity can be so realized in a simple manner that an adjustable stop or abutment is provided for the purpose of limitation of the cylinder stroke, which periodically eliminates the force-locking engagement between the control pin and the cylinder surface whereby a screw adapted to be screwed into the bolt to different depths may serve as abutment.

An increase in the number of lubricating oil lines adapted to be supplied can be achieved with the pump construction of the type described above in that two fixed pistons and therewith three working spaces are arranged in series, i.e., axially one behind the other. Already with a guidance of the control pin by means of a flat control surface, three lubricating oil lines can be supplied with 3,510,235 Patented May 5, 1970 "Ice the aid of this feature of the present invention, and with the use of a cylindrical guide surface even six lubricating oil lines.

Accordingly, it is an object of the present invention to provide a piston pump of the type described above which eliminates the aforementioned shortcomings and drawbacks encountered in the prior art by extremely simple means.

Another object of the present invention resides in 'a piston pump which permits an increase in the number of oil lines supplied per pump working space.

A further object of the present invention resides in a piston pump which doubles the number of oil lines whose supply is metered without any requirements as regards additional weight or space.

A still further object of the present invention resides in a piston pump of the type described above which not only results in simple manufacture and assembly but also entails the advantage of simple adjustment of the pump cylinder stroke.

These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, two embodiments in accordance with the present invention, and wherein:

FIG. 1 is an axial longitudinal cross-sectional view through an oil-lubricating pump in accordance with the present invention;

FIG. 2 is a cross-sectional view, on an enlarged scale, through the bolt with the cylinder surface for the guidance of the control pin;

FIG. 3 is a cross-sectional view, taken along line III-III of FIG. 1;

FIG. 4 is a cross-sectional view taken along line IVIV of FIG. 1;

FIG. 5 is a partial longitudinal cross-sectional view through a modified embodiment of an oil-lubricating pump in accordance with the present invention having two fixed pistons; and

FIG. 6 is a cross-sectional view taken along line VIVI of FIG. 5.

Referring now to the drawing wherein like reference numerals are used throughout the various views to designate like parts and more particularly to FIG. 1, the input or drive shaft 11 together with the worm 12 is supported in a conventional manner in the pump housing 10. The worm 12 is in operative engagement with a worm wheel 13 which is in driving connection with the pump cylinder 15 by way of a pin 14. The pin 14 rigidly connects the cylinder 15 with a bolt 16 axially pressed into the cylinder 15. The bolt 16 axially projects above the cylinder 15 with a collar 17 thereof. A control pin 18 is provided on the collar 17 eccentrically to the cylinder axis.

The pump cylinder 15 is supported in a bush 19 which is pressed into support member 20 that, in its turn, is again securely connected with the pump housing 10. A bottom plate 21 is arranged at the lower end of the bush 19 fixed to the housing.

The pin 14 is able to move axially within a slot of the worm wheel 13 relative to the latter. In contrast thereto, the slot does not permit of any relative rotary movement between the worm gear 13 and the pump cylinder 15.

The fixed piston 22 is force-lockingly supported on the bottom plate 21 under a certain pivoting possibility desirable for assembly reasons. The piston 22 is continuously pressed by a compression spring 23 against its seat in the bottom plate 21.

A spring 23 between the worm gear 13 and the collar 17 assures that the pump cylinder 15 together with the structural elements rigidly connected therewith is constantly pressed by way of the control pin 18 against a bolt 24 which is securely seated in the pump housing 10. As can be seen in particular from FIG. 2, the control pin 18 abuts against a cylinder surface 25 which has a larger radius 25 than the bolt 24 with its radius 24'.

A screw 27 is screwed into the bolt 24 which projects with an extension 27' more or less beyond the circum ference of the cylinder surface 25. The path of the adjusting screw 27 is limited by an inserted adjusting disk 28. The adjusting screw 27 can be adjusted with the aid of a rotatable adjusting bolt 29 which engages with an extension 30 in a slot within the head of the adjusting screw 27. This takes place with the aid of a hand lever 31 which is adapted to be placed over the bolt 29 in the desired position by way of a spline tooth arrangement 32.

The interior of the pump is continuously filled with oil by way of an oil supply line 10'. The oil also reaches therefore two axial bores 33 and 34 in the support member 20 from where, as can be clearly seen from FIG. 1 and 4, it can reach up to the outer wall of the pump cylinder 15. One small bore 39 each is disposed in the pump cylinder 15 at the height of the connections 35 and 36 and of the conections 37 and 38, respectively, for the pressure lines to the lubricating places. The bores 39 lead to the two working spaces 40 and 41.

OPERATION The operation of the pump is as follows:

The pump cylinder 15 together with the bolt 16, the collar 17 thereof and the control pin 18 is set into rotation by the worm drive 12 and 13. Since the spring 23- constantly presses this entire assembly in the upward direction, the pump cylinder 15 carries out two complete stroke movements during one complete rotation, for the control pin 18 thereby moves twice over that surface line of the cylinder superficies 25 which intersects with the longitudinal axis of the pump cylinder 15. During these stroke movements of the pump cylinder 15, the working spaces 40 and 41 are periodically enlarged and reduced. Care is now taken that during the rotation of the pump cylinder 15, the bores or apertures 39' pass over the wide bores 42 and 43 during the enlargement of the work spaces 40 and 41, respectively, and therewith enagle a sucking-in of the oil into the enlarging working spaces. During the reduction of the working spaces, the apertures 39 then pass over the wide bores 44 and 45, respectively, through which the oil is forced under pressure into the connections 38 and 37 and into connections 36- and 35, respectively.

The stroke of the pump piston and therewith the oil volume supplied per stroke can be adjusted in that one causes the screw 27 to project more or less with its extension 27' out of the cylinder surface 25. The further this extension 27' projects, the sooner the collar 17 will come into abutment against the same and will thus prevent that the control pin 18 further moves upwardly. Consequently, the control pin 18 lifts off for a short period of time from its guide surface 25 until it is seized again by the guide surface 25 during the further rotation.

In the embodiment according to FIGS. and 6, two fixed pump pistons 46 and 47 are provided so that three working spaces 48, 49 and 50 result. The stroke control is to be thought of in this embodiment as of conventional construction in which only one stroke movement is produced during a complete rotation of the pump cylinder. Consequently, only one pressure oil connection is coordinated to each working space. However, it is also feasible without difficulty that two pressure lines could be coordinated to each working space, as in the embodiment according to FIGS. 1 to 4, by the use of the drive mechanism illustrated therein whereby altogether six pressure connections would be achievable in a simple and space-saving maner.

While we have shown and described only two embodiments in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to a person skilled in the art, for example, the guide surface 25 may also deviate from a generated surface, and we therefore do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are within the scope of those skilled in the art.

It is claimed:

1. A piston pump which includes fixed piston means and reciprocating and simultaneously rotating pump cylinder means controlling the inlet and outlet means of the pump, and means for deriving the stroke movement of-the cylinder means from the rotary movement imparted thereto including force-locking guide means, characterized in that the force-locking guide means includes eccentric control pin means operatively connected with said cylinder means and engaging on a control surface means, and said control surface means having a curved surface producing two reciprocations of the cylinder means per revolution thereof.

2. A piston pump according to claim 1, wherein said control surface means has approximately the shape of a cylindrical surface.

'3. A piston pump according to claim 2, wherein the control surface means is provided at a bolt means inserted into the pump housing substantially transversely to the pump cylinder axis, the radius of the control surface means being larger than the radius of the bolt means.

4. A piston pump according to claim 3, further comprising adjustable abutment means for limiting the cylinder stroke which periodically suspends the force-locking engagement between the control pin means and the control surface means.

5. A piston pump according to claim 4, wherein a screw adapted to be screwed into the bolt means to different depths serves as abutment means.

6. A piston pump according to claim 5, wherein two fixed piston means and therewith three working spaces arranged behind one another are provided within the pump.

7.A piston pump according to claim 1, wherein the control surface means is provided at an insert means inserted into the pump housing substantially transversely to the pump cylinder axis, the radius of the control surface means being larger than the radius of the bolt means.

8. A piston pump according to claim 7, further comprising adjustable abutment means for limiting the cylinder stroke which periodically suspends the force-locking engagement between the control pin means and the control surface means.

9. A piston pump according to claim 8, wherein two fixed piston means and therewith three working spaces arranged behind one another are provided within the pump.

10. A piston pump according to claim 1, further comprising adjustable abutment means for limiting the cylinder stroke which periodically suspends the force-locking engagement between the control pin means and the control surface means.

11. A piston pump according to claim 10, wherein a screw adapted to be screwed into different depths serves as abutment means.

12. A piston pump according to claim 1, wherein two fixed piston means and therewith three working spaces arranged behind one another are provided within the pump.

13. A piston pump according to claim 12, wherein said control surface means has approximately the shape of a cylindrical surface.

14. A piston pump which includes fixed piston means and reciprocating and simultaneously rotating pump cylinder means controlling the inlet and outlet means of the pump, and means for deriving the stroke movement of the cylinder means from the rotary movement imparted thereto including force-locking guide means, characterized in that two fixed piston means are provided in the cylinder means thereby forming three working spaces disposed one behind the other in the axial direction.

15. A piston pump according to claim 14, wherein an approximatley cylindrically shaped control surface is provided in the pump housing with which engages the force-locking guide means to impart to the cylinder means two reciprocations per revolution.

16. A piston pump according to claim 15, further comprising adjustable means for limiting the cylinder stroke which periodically suspends the force-locking engagement between the control pin means and the control surface.

FOREIGN PATENTS 718,314 11/1954 Great Britain.

HENRY F. RADUAZO, Primary Examiner US. Cl. X.R. 

